In order to attain the effective use of limited resources, there have been proposed technologies for taking out electric energy through conversion of various types of energy. One of them is technology for taking out electric energy through conversion of vibration energy. For example, Patent Document 1 given below discloses a piezoelectric-type power generating element in which a layered piezoelectric element is laminated to form a piezoelectric element for power generation, and an external force is used to cause the piezoelectric element for power generation to vibrate, thereby generating electric power. Further, Patent Document 2 discloses a power generating element which has an MEMS (Micro Electro Mechanical System) structure using a silicon substrate.
A basic principle of the above-described power generating elements is to impart periodic deflection to a piezoelectric element by vibration of a weight body, thereby taking out to the outside charge generated on the basis of stress applied to the piezoelectric element. The above-described power generating element is mounted on automobiles, trains and ships, for example, by which it is possible to take out vibration energy applied during transportation as electric energy. The power generating element can be mounted on vibration sources such as refrigerators and air conditioners, thereby generating electric power.